1 // SPDX-License-Identifier: GPL-2.0 2 // Copyright (c) 2017 Facebook 3 #include <stddef.h> 4 #include <stdbool.h> 5 #include <string.h> 6 #include <linux/pkt_cls.h> 7 #include <linux/bpf.h> 8 #include <linux/in.h> 9 #include <linux/if_ether.h> 10 #include <linux/ip.h> 11 #include <linux/ipv6.h> 12 #include <linux/icmp.h> 13 #include <linux/icmpv6.h> 14 #include <linux/tcp.h> 15 #include <linux/udp.h> 16 #include <bpf/bpf_helpers.h> 17 #include "test_iptunnel_common.h" 18 #include <bpf/bpf_endian.h> 19 20 #include "bpf_kfuncs.h" 21 22 static __always_inline __u32 rol32(__u32 word, unsigned int shift) 23 { 24 return (word << shift) | (word >> ((-shift) & 31)); 25 } 26 27 /* copy paste of jhash from kernel sources to make sure llvm 28 * can compile it into valid sequence of bpf instructions 29 */ 30 #define __jhash_mix(a, b, c) \ 31 { \ 32 a -= c; a ^= rol32(c, 4); c += b; \ 33 b -= a; b ^= rol32(a, 6); a += c; \ 34 c -= b; c ^= rol32(b, 8); b += a; \ 35 a -= c; a ^= rol32(c, 16); c += b; \ 36 b -= a; b ^= rol32(a, 19); a += c; \ 37 c -= b; c ^= rol32(b, 4); b += a; \ 38 } 39 40 #define __jhash_final(a, b, c) \ 41 { \ 42 c ^= b; c -= rol32(b, 14); \ 43 a ^= c; a -= rol32(c, 11); \ 44 b ^= a; b -= rol32(a, 25); \ 45 c ^= b; c -= rol32(b, 16); \ 46 a ^= c; a -= rol32(c, 4); \ 47 b ^= a; b -= rol32(a, 14); \ 48 c ^= b; c -= rol32(b, 24); \ 49 } 50 51 #define JHASH_INITVAL 0xdeadbeef 52 53 typedef unsigned int u32; 54 55 static __noinline u32 jhash(const void *key, u32 length, u32 initval) 56 { 57 u32 a, b, c; 58 const unsigned char *k = key; 59 60 a = b = c = JHASH_INITVAL + length + initval; 61 62 while (length > 12) { 63 a += *(u32 *)(k); 64 b += *(u32 *)(k + 4); 65 c += *(u32 *)(k + 8); 66 __jhash_mix(a, b, c); 67 length -= 12; 68 k += 12; 69 } 70 switch (length) { 71 case 12: c += (u32)k[11]<<24; 72 case 11: c += (u32)k[10]<<16; 73 case 10: c += (u32)k[9]<<8; 74 case 9: c += k[8]; 75 case 8: b += (u32)k[7]<<24; 76 case 7: b += (u32)k[6]<<16; 77 case 6: b += (u32)k[5]<<8; 78 case 5: b += k[4]; 79 case 4: a += (u32)k[3]<<24; 80 case 3: a += (u32)k[2]<<16; 81 case 2: a += (u32)k[1]<<8; 82 case 1: a += k[0]; 83 __jhash_final(a, b, c); 84 case 0: /* Nothing left to add */ 85 break; 86 } 87 88 return c; 89 } 90 91 static __noinline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval) 92 { 93 a += initval; 94 b += initval; 95 c += initval; 96 __jhash_final(a, b, c); 97 return c; 98 } 99 100 static __noinline u32 jhash_2words(u32 a, u32 b, u32 initval) 101 { 102 return __jhash_nwords(a, b, 0, initval + JHASH_INITVAL + (2 << 2)); 103 } 104 105 #define PCKT_FRAGMENTED 65343 106 #define IPV4_HDR_LEN_NO_OPT 20 107 #define IPV4_PLUS_ICMP_HDR 28 108 #define IPV6_PLUS_ICMP_HDR 48 109 #define RING_SIZE 2 110 #define MAX_VIPS 12 111 #define MAX_REALS 5 112 #define CTL_MAP_SIZE 16 113 #define CH_RINGS_SIZE (MAX_VIPS * RING_SIZE) 114 #define F_IPV6 (1 << 0) 115 #define F_HASH_NO_SRC_PORT (1 << 0) 116 #define F_ICMP (1 << 0) 117 #define F_SYN_SET (1 << 1) 118 119 struct packet_description { 120 union { 121 __be32 src; 122 __be32 srcv6[4]; 123 }; 124 union { 125 __be32 dst; 126 __be32 dstv6[4]; 127 }; 128 union { 129 __u32 ports; 130 __u16 port16[2]; 131 }; 132 __u8 proto; 133 __u8 flags; 134 }; 135 136 struct ctl_value { 137 union { 138 __u64 value; 139 __u32 ifindex; 140 __u8 mac[6]; 141 }; 142 }; 143 144 struct vip_meta { 145 __u32 flags; 146 __u32 vip_num; 147 }; 148 149 struct real_definition { 150 union { 151 __be32 dst; 152 __be32 dstv6[4]; 153 }; 154 __u8 flags; 155 }; 156 157 struct vip_stats { 158 __u64 bytes; 159 __u64 pkts; 160 }; 161 162 struct eth_hdr { 163 unsigned char eth_dest[ETH_ALEN]; 164 unsigned char eth_source[ETH_ALEN]; 165 unsigned short eth_proto; 166 }; 167 168 struct { 169 __uint(type, BPF_MAP_TYPE_HASH); 170 __uint(max_entries, MAX_VIPS); 171 __type(key, struct vip); 172 __type(value, struct vip_meta); 173 } vip_map SEC(".maps"); 174 175 struct { 176 __uint(type, BPF_MAP_TYPE_ARRAY); 177 __uint(max_entries, CH_RINGS_SIZE); 178 __type(key, __u32); 179 __type(value, __u32); 180 } ch_rings SEC(".maps"); 181 182 struct { 183 __uint(type, BPF_MAP_TYPE_ARRAY); 184 __uint(max_entries, MAX_REALS); 185 __type(key, __u32); 186 __type(value, struct real_definition); 187 } reals SEC(".maps"); 188 189 struct { 190 __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY); 191 __uint(max_entries, MAX_VIPS); 192 __type(key, __u32); 193 __type(value, struct vip_stats); 194 } stats SEC(".maps"); 195 196 struct { 197 __uint(type, BPF_MAP_TYPE_ARRAY); 198 __uint(max_entries, CTL_MAP_SIZE); 199 __type(key, __u32); 200 __type(value, struct ctl_value); 201 } ctl_array SEC(".maps"); 202 203 static __noinline __u32 get_packet_hash(struct packet_description *pckt, bool ipv6) 204 { 205 if (ipv6) 206 return jhash_2words(jhash(pckt->srcv6, 16, MAX_VIPS), 207 pckt->ports, CH_RINGS_SIZE); 208 else 209 return jhash_2words(pckt->src, pckt->ports, CH_RINGS_SIZE); 210 } 211 212 static __noinline bool get_packet_dst(struct real_definition **real, 213 struct packet_description *pckt, 214 struct vip_meta *vip_info, 215 bool is_ipv6) 216 { 217 __u32 hash = get_packet_hash(pckt, is_ipv6); 218 __u32 key = RING_SIZE * vip_info->vip_num + hash % RING_SIZE; 219 __u32 *real_pos; 220 221 if (hash != 0x358459b7 /* jhash of ipv4 packet */ && 222 hash != 0x2f4bc6bb /* jhash of ipv6 packet */) 223 return false; 224 225 real_pos = bpf_map_lookup_elem(&ch_rings, &key); 226 if (!real_pos) 227 return false; 228 key = *real_pos; 229 *real = bpf_map_lookup_elem(&reals, &key); 230 if (!(*real)) 231 return false; 232 return true; 233 } 234 235 static __noinline int parse_icmpv6(struct bpf_dynptr *skb_ptr, __u64 off, 236 struct packet_description *pckt) 237 { 238 __u8 buffer[sizeof(struct ipv6hdr)] = {}; 239 struct icmp6hdr *icmp_hdr; 240 struct ipv6hdr *ip6h; 241 242 icmp_hdr = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 243 if (!icmp_hdr) 244 return TC_ACT_SHOT; 245 246 if (icmp_hdr->icmp6_type != ICMPV6_PKT_TOOBIG) 247 return TC_ACT_OK; 248 off += sizeof(struct icmp6hdr); 249 ip6h = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 250 if (!ip6h) 251 return TC_ACT_SHOT; 252 pckt->proto = ip6h->nexthdr; 253 pckt->flags |= F_ICMP; 254 memcpy(pckt->srcv6, ip6h->daddr.s6_addr32, 16); 255 memcpy(pckt->dstv6, ip6h->saddr.s6_addr32, 16); 256 return TC_ACT_UNSPEC; 257 } 258 259 static __noinline int parse_icmp(struct bpf_dynptr *skb_ptr, __u64 off, 260 struct packet_description *pckt) 261 { 262 __u8 buffer_icmp[sizeof(struct iphdr)] = {}; 263 __u8 buffer_ip[sizeof(struct iphdr)] = {}; 264 struct icmphdr *icmp_hdr; 265 struct iphdr *iph; 266 267 icmp_hdr = bpf_dynptr_slice(skb_ptr, off, buffer_icmp, sizeof(buffer_icmp)); 268 if (!icmp_hdr) 269 return TC_ACT_SHOT; 270 if (icmp_hdr->type != ICMP_DEST_UNREACH || 271 icmp_hdr->code != ICMP_FRAG_NEEDED) 272 return TC_ACT_OK; 273 off += sizeof(struct icmphdr); 274 iph = bpf_dynptr_slice(skb_ptr, off, buffer_ip, sizeof(buffer_ip)); 275 if (!iph || iph->ihl != 5) 276 return TC_ACT_SHOT; 277 pckt->proto = iph->protocol; 278 pckt->flags |= F_ICMP; 279 pckt->src = iph->daddr; 280 pckt->dst = iph->saddr; 281 return TC_ACT_UNSPEC; 282 } 283 284 static __noinline bool parse_udp(struct bpf_dynptr *skb_ptr, __u64 off, 285 struct packet_description *pckt) 286 { 287 __u8 buffer[sizeof(struct udphdr)] = {}; 288 struct udphdr *udp; 289 290 udp = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 291 if (!udp) 292 return false; 293 294 if (!(pckt->flags & F_ICMP)) { 295 pckt->port16[0] = udp->source; 296 pckt->port16[1] = udp->dest; 297 } else { 298 pckt->port16[0] = udp->dest; 299 pckt->port16[1] = udp->source; 300 } 301 return true; 302 } 303 304 static __noinline bool parse_tcp(struct bpf_dynptr *skb_ptr, __u64 off, 305 struct packet_description *pckt) 306 { 307 __u8 buffer[sizeof(struct tcphdr)] = {}; 308 struct tcphdr *tcp; 309 310 tcp = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 311 if (!tcp) 312 return false; 313 314 if (tcp->syn) 315 pckt->flags |= F_SYN_SET; 316 317 if (!(pckt->flags & F_ICMP)) { 318 pckt->port16[0] = tcp->source; 319 pckt->port16[1] = tcp->dest; 320 } else { 321 pckt->port16[0] = tcp->dest; 322 pckt->port16[1] = tcp->source; 323 } 324 return true; 325 } 326 327 static __noinline int process_packet(struct bpf_dynptr *skb_ptr, 328 struct eth_hdr *eth, __u64 off, 329 bool is_ipv6, struct __sk_buff *skb) 330 { 331 struct packet_description pckt = {}; 332 struct bpf_tunnel_key tkey = {}; 333 struct vip_stats *data_stats; 334 struct real_definition *dst; 335 struct vip_meta *vip_info; 336 struct ctl_value *cval; 337 __u32 v4_intf_pos = 1; 338 __u32 v6_intf_pos = 2; 339 struct ipv6hdr *ip6h; 340 struct vip vip = {}; 341 struct iphdr *iph; 342 int tun_flag = 0; 343 __u16 pkt_bytes; 344 __u64 iph_len; 345 __u32 ifindex; 346 __u8 protocol; 347 __u32 vip_num; 348 int action; 349 350 tkey.tunnel_ttl = 64; 351 if (is_ipv6) { 352 __u8 buffer[sizeof(struct ipv6hdr)] = {}; 353 354 ip6h = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 355 if (!ip6h) 356 return TC_ACT_SHOT; 357 358 iph_len = sizeof(struct ipv6hdr); 359 protocol = ip6h->nexthdr; 360 pckt.proto = protocol; 361 pkt_bytes = bpf_ntohs(ip6h->payload_len); 362 off += iph_len; 363 if (protocol == IPPROTO_FRAGMENT) { 364 return TC_ACT_SHOT; 365 } else if (protocol == IPPROTO_ICMPV6) { 366 action = parse_icmpv6(skb_ptr, off, &pckt); 367 if (action >= 0) 368 return action; 369 off += IPV6_PLUS_ICMP_HDR; 370 } else { 371 memcpy(pckt.srcv6, ip6h->saddr.s6_addr32, 16); 372 memcpy(pckt.dstv6, ip6h->daddr.s6_addr32, 16); 373 } 374 } else { 375 __u8 buffer[sizeof(struct iphdr)] = {}; 376 377 iph = bpf_dynptr_slice(skb_ptr, off, buffer, sizeof(buffer)); 378 if (!iph || iph->ihl != 5) 379 return TC_ACT_SHOT; 380 381 protocol = iph->protocol; 382 pckt.proto = protocol; 383 pkt_bytes = bpf_ntohs(iph->tot_len); 384 off += IPV4_HDR_LEN_NO_OPT; 385 386 if (iph->frag_off & PCKT_FRAGMENTED) 387 return TC_ACT_SHOT; 388 if (protocol == IPPROTO_ICMP) { 389 action = parse_icmp(skb_ptr, off, &pckt); 390 if (action >= 0) 391 return action; 392 off += IPV4_PLUS_ICMP_HDR; 393 } else { 394 pckt.src = iph->saddr; 395 pckt.dst = iph->daddr; 396 } 397 } 398 protocol = pckt.proto; 399 400 if (protocol == IPPROTO_TCP) { 401 if (!parse_tcp(skb_ptr, off, &pckt)) 402 return TC_ACT_SHOT; 403 } else if (protocol == IPPROTO_UDP) { 404 if (!parse_udp(skb_ptr, off, &pckt)) 405 return TC_ACT_SHOT; 406 } else { 407 return TC_ACT_SHOT; 408 } 409 410 if (is_ipv6) 411 memcpy(vip.daddr.v6, pckt.dstv6, 16); 412 else 413 vip.daddr.v4 = pckt.dst; 414 415 vip.dport = pckt.port16[1]; 416 vip.protocol = pckt.proto; 417 vip_info = bpf_map_lookup_elem(&vip_map, &vip); 418 if (!vip_info) { 419 vip.dport = 0; 420 vip_info = bpf_map_lookup_elem(&vip_map, &vip); 421 if (!vip_info) 422 return TC_ACT_SHOT; 423 pckt.port16[1] = 0; 424 } 425 426 if (vip_info->flags & F_HASH_NO_SRC_PORT) 427 pckt.port16[0] = 0; 428 429 if (!get_packet_dst(&dst, &pckt, vip_info, is_ipv6)) 430 return TC_ACT_SHOT; 431 432 if (dst->flags & F_IPV6) { 433 cval = bpf_map_lookup_elem(&ctl_array, &v6_intf_pos); 434 if (!cval) 435 return TC_ACT_SHOT; 436 ifindex = cval->ifindex; 437 memcpy(tkey.remote_ipv6, dst->dstv6, 16); 438 tun_flag = BPF_F_TUNINFO_IPV6; 439 } else { 440 cval = bpf_map_lookup_elem(&ctl_array, &v4_intf_pos); 441 if (!cval) 442 return TC_ACT_SHOT; 443 ifindex = cval->ifindex; 444 tkey.remote_ipv4 = dst->dst; 445 } 446 vip_num = vip_info->vip_num; 447 data_stats = bpf_map_lookup_elem(&stats, &vip_num); 448 if (!data_stats) 449 return TC_ACT_SHOT; 450 data_stats->pkts++; 451 data_stats->bytes += pkt_bytes; 452 bpf_skb_set_tunnel_key(skb, &tkey, sizeof(tkey), tun_flag); 453 *(u32 *)eth->eth_dest = tkey.remote_ipv4; 454 return bpf_redirect(ifindex, 0); 455 } 456 457 SEC("tc") 458 int balancer_ingress(struct __sk_buff *ctx) 459 { 460 __u8 buffer[sizeof(struct eth_hdr)] = {}; 461 struct bpf_dynptr ptr; 462 struct eth_hdr *eth; 463 __u32 eth_proto; 464 __u32 nh_off; 465 int err; 466 467 nh_off = sizeof(struct eth_hdr); 468 469 bpf_dynptr_from_skb(ctx, 0, &ptr); 470 eth = bpf_dynptr_slice_rdwr(&ptr, 0, buffer, sizeof(buffer)); 471 if (!eth) 472 return TC_ACT_SHOT; 473 eth_proto = eth->eth_proto; 474 if (eth_proto == bpf_htons(ETH_P_IP)) 475 err = process_packet(&ptr, eth, nh_off, false, ctx); 476 else if (eth_proto == bpf_htons(ETH_P_IPV6)) 477 err = process_packet(&ptr, eth, nh_off, true, ctx); 478 else 479 return TC_ACT_SHOT; 480 481 if (eth == buffer) 482 bpf_dynptr_write(&ptr, 0, buffer, sizeof(buffer), 0); 483 484 return err; 485 } 486 487 char _license[] SEC("license") = "GPL"; 488